This invention relates to a hydraulic system of a combine and the hydraulic systems of harvesting assemblies attached to the front of the combines.
Agricultural combine harvesters are provided with harvesting assemblies at the front of the vehicles. The harvesting assemblies engage the crop in the field being harvested and direct the crop into the combine vehicle for processing. Various different harvesting assemblies can be coupled to the front of the combine so that different crops can be harvested. For example, a corn harvesting head is used to snap the stalks of corn downwardly to strip the ears of corn from the stalks, and transport the ears of corn to the combine vehicle where the kernels of corn are separated from the corn cob. Other types of harvesting assemblies include row crop headers, pickup platforms, rigid harvesting platforms, flex harvesting platforms, and draper harvesting platforms.
The type of harvesting assembly known as a harvesting platform or cutting platform is used to harvest crops such as wheat. The cutting platform includes a cutter bar that cuts the wheat near the ground surface and a conveyor that transports the cut crop to the combine for separation of the grains of wheat from the rest of the plant. These cutting platforms include a reel that rotates about a horizontal and laterally extending axis. The reel gently directs the crop rearwardly against the cutter bar, and that also helps direct the cut crop further rearwardly onto the conveyor. The reels are typically driven hydraulically by a reel drive motor mounted on the cutting platform. The hydraulic motor receives hydraulic fluid under pressure from the hydraulic system carried by the combine vehicle. Conventional combine vehicles include a hydraulic pump which supplies fluid under pressure via a hydraulic hose line to the reel drive motor. A hydraulic fluid return line extends from the reel drive motor to the hydraulic system on the combine vehicle. Hydraulic quick couplings are provided in both the supply and return lines so that the cutting unit can be hydraulically detached from the combine vehicle. When the cutting platform is removed from the combine vehicle, the couplings are uncoupled, which disengages the cutting platform""s hydraulic lines from the combine vehicle""s hydraulic system.
The pump will run continuously when the combine is running, and will pressurize the fluid in the fluid supply line whether there is a corn head or cutting platform attached to the combine. When the cutting platform is attached, the fluid in the supply line flows through the coupling and through the reel drive motor carried by the cutting platform. The exhausted fluid then is routed through the cutting platform""s return line, through the return line coupling, and through the combine""s return line until it is eventually routed back to the combine hydraulic system""s reservoir.
Certain corn heads do not utilize the hydraulic supply and return lines referred to above which drive reel drive motors of cutting platforms. So when a corn head is attached to the combine vehicle, no hydraulic lines from the corn head are coupled to the hydraulic fluid supply and return lines of the combine vehicle. When a corn head is attached to the combine, the pump will continue to pressurize the fluid in the supply line, even though the supply line effectively dead ends at the coupling. Between the pump and the supply line coupling is a control valve that includes a pressure relief valve. The pump will generate enough pressure in the supply line that the relief valve will be actuated, causing fluid to flow through the relief valve and into the reservoir. This mode of operation tends to place large stresses on the pump, causes heat buildup in the system, and can lead to pump failure. To eliminate this problem, combine operators need to manually connect the combine""s supply line to the return line when corn heads are attached to the combine. The operator can do this by attaching one end of a short hose line to the supply line coupling and the other end to the return line coupling. This eliminates the dead end at the supply line coupling and allows fluid to flow from the supply line coupling directly into the return line coupling. Fluid is thereby allowed to flow to the hydraulic system reservoir, which relieves the stress on the pump and overheating otherwise associated with the supply line dead ending. However, the operator does not always remember to perform this operation, which can lead to premature pump failure as described above. When the operator does remember to couple the combine""s supply line to the return line when he is attaching the corn head to the combine, the operation undesirably adds to the time it takes to change combine harvesting assemblies.
It would therefore be desirable to provide a mechanism which eliminates the inconveniences of attaching a bypass line between the supply line coupler and the return line coupler when a corn head is to be used, and which eliminates the problem of heat buildup, stress and failure of the pumps when the supply line effectively dead ends at its coupler.
In accordance with the present invention, a shunt or passageway is provided that automatically allows fluid to flow from the combine supply line directly to the combine return line when no harvester assembly hydraulic line is coupled with the combine supply line. A multicoupler is provided having two halves, one carried by the combine vehicle and the other carried by a cutting platform. When the cutting platform is attached to the combine, the two halves of the multicoupler are joined together, thus coupling a plurality of hydraulic lines together, including the combine supply line with the platform supply line, and the combine return line with the platform return line. When the platform supply line is engaged with the combine supply line in this manner, a valve mechanism housed within the body of the combine half of the multicoupler allows fluid to flow as described from the combine supply line to the platform supply line, and from the platform return line to the combine return line.
The cutting platform can be detached from the combine vehicle and replaced with a corn head. To do so the two halves of the multicoupler are detached from one another, the cutting platform is removed from the combine vehicle, and a corn head is installed. The corn head will not utilize the combine supply line or return line, and therefore those ports in the combine half of the multicoupler will not have any hydraulic lines attached to them when a corn head is attached to the combine. When no platform hydraulic line is attached to the combine hydraulic fluid supply line, the valve mechanism housed in the combine half of the multicoupler will orient itself to route fluid from the combine supply line to the combine return line within the housing of the combine half of the multicoupler. The valve routes fluid from the combine supply line into the shunt or passageway, which in turn directs the fluid to the combine return line and back to the hydraulic system reservoir. This eliminates pressure buildup in the supply line that would otherwise be caused by dead ending of the combine supply line, and allows fluid from the pump to flow back to the reservoir. This reduces heat buildup and stress on the pump. The valve automatically routes fluid through the shunt in this manner, and therefore the operator is not required to manually perform the additional task of attaching the hydraulic lines to one another. The process of changing harvesting assemblies is therefore simplified, and the time required to change harvesting assemblies is correspondingly reduced.